Understanding Signals with the PropScope - Chapter 2: DC Measurements (Draft Copy)

Andy Lindsay (Parallax)

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Thanks to all our reviewers for their input!

John Abshier

What about the Propeller? If not in the main text, how about an appendix with figures for Demo Board or Education Kit and Spin code examples.

John Abshier

sylvie369

Okay, I'm not working along (as I don't have a Propscope yet), but something looks wrong in Figure 2.7. It looks identical to Figure 2.3.
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Shouldn't the CH1 wire be in the Vdd connector, and the CH2 wire in the Vin connector? And the little schematic adjusted to reflect those connections?
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And on p. 49 near the bottom you have "In brief, a potentiometer has a resistive element that spans it’s A and B terminals".
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That should be "...that spans its A and B terminals" (no·apostrophe on "its").
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On p. 50 near the top, you have "The sum of these to resistances will always add up to the resistance between A and B"
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That should, of course, be "of these two resistances".
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P. 51 - the box reads "Another Option: Connect ground clips to the plated holes at the corners of Your board. Like the Vss sockets, the metal in the plated holes at the each corner of your board are also connected to your board’s negative power terminal, so they are also Vss connections."

Might this be a good place to point out that many boards like the Propeller Professional Development Board have built-in ground connections for oscilloscope use?

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P. 52 - "A BASIC Stamp I/O pin set to input interprets voltages above 1.4 V as binary-1 and below 1.4 V as binary-0."

That might be slightly less confusing with the hyphens removed ("as binary 1 and...as binary 0"), as they could be interpreted as minus signs.

(See my comment on the Ch 4 draft: apparently the document is inconsisent in how these are labeled. A standard is needed).

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P. 53 - The box includes this "and the resulting current the I/O pin would try to supply the circuit trying to pull the 0 V ground connection up to 5 V would quickly damage the I/O pin."

How about this instead? "and the resulting current would quickly damage the I/O pin, as the the pin would try to supply current to pull the 0 V ground connection up to 5 V".

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Post Edited (sylvie369) : 7/28/2010 6:26:16 PM GMT

Andy Lindsay (Parallax)

sylvie369,

This is great material! Thank you. All has been duly noted and queued for the next edit. I should have the Chapter 5 draft up tonight. After that, I'll be taking a 1 week break, and will resume posting chapters 6-9 starting either Thursday, 8/5 or Friday, 8/6.

Andy

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Andy Lindsay

Education Department
Parallax, Inc.

Andy Lindsay (Parallax)

Figure 2-7 corrected in Chapter 2. Correction in DRAFT 421 attached to first post.